Frangible key for locking alarm signal stations



July 1 1966 J. H. FASAL ETAL FRANGIBLE KEY FOR LOCKING ALARM SIGNAL STATIONS Filed March 4, 1964 INVENTORS J OHN H- FA SA L CH AR LES E. ZIMMERMAN,JR

- ATTORNEY United States Patent 3,260,831 FRANGELE KEY FOR LQCKING ALARM SIGNAL STATIONS John H. Fasal, New York, N.Y., and Charles Emanuel Zimmerman, In, West Caldwell, N.J., assignors to Specialties Development Corporation, Belleville, N.J., a corporation of New Jersey Filed Mar. 4, 1964, Ser. No. 349,351

17 Claims. (Cl. 200-168) areas to be protected.

Accordingly, an object of the present invention is to provide an extremely simple, inexpensive arrangement for reliably performing all of the required functions of the prior apparatus.

Another object is to provide such an arrangement which locks .the signal station securely before an alarm is to be given but can be readily unlocked to give an alarm.

Another object is to provide such an arrangement which can only be reset by authorized persons and remains unlocked if tampered with by unauthorized persons.

A. further object is to provide such an arrangement which can betested by authorized persons without destruction of parts for locking the signal station.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

FIG. 1 is a front elevational view of apparatus in accordance with the present invention.

I FIG. 2 is a sectional view taken along the line 22 of FIG. 1.

FIG. 3 is a fragmentary rear elevational view of a member for mounting the apparatus on wall structure.

FIG. 4 is a fragmentary elevational view taken along the line 44 on FIG. 2.

FIG. 5 is a fragmentary plan view of the apparatus.

A FIG. 6 is a perspective view of a key for use in connection with the apparatus.

Referring now to the drawing in detail, alarm signal station apparatus is shown which generally comprises a back plate 10 for mounting the apparatus on wall structure W (FIG. 2), a switch 11 mounted on the plate 10, a boxlike front member 12 cooperating with the plate 10 to provide a box and closure for concealing and enclosing the switch, hinge means 14 for pivotally connecting the lower edge of the front member on the lower edge of the plate to enable the box to be opened, and a locking arrangement generally indicated by the reference number 15 which will be described indetail hereinafter.

The back plate 10 (FIGS. 2 and 3) is rectangular and is provided with holes 13 for receiving screws 16 shown herein as being secured in the wall structure W for the sake of simple illustration, although in actual practice the back plate would be fastened to a standard electrical box in turn mounted on a wall and thus serving as wall structure.

The switch 11 (FIG. 2) extends through and is secured to the plate 10 at about the middle thereof. Preferably, although not necessarily, the switch is of the push button type having a movable spring urged switch operating element 17 at the front thereof which is engaged by the front member 12 to respectively either open or close the switch when the box is closed and to allow the switch to either close or when the box is opened to control an alarm circuit (not shown). Alternatively, the switch could be of the type which is operated at will when made accessible by opening the box.

The front member 12 also is rectangular and preferably is hinged at its lower edge to the lower edge of the plate 10. The front member has a top wall 18, a bottom wall 19, side walls 20, and a front wall 21. The front and side walls have portions extending above the top wall to provide structure serving as a pull handle H and to conceal the top wall for the purposes described hereinafter.

The locking arrangement 15 includes a boss 22 which extends rearwardly from the back of the front wall 21 to about the front of the plate 10 (FIGS. 2 and 5) and is formed with upper and lower recesses 23a and 23b at the front and with a keyway 24 extending therethrough; a

slot 25 in the plate 10 which registers with the keyway when the box is closed; and a key 26 (FIG. 6) extending through the keyway 24 and structurally independent of the front member 12 and the plate 10, and the slot 25 which has a frangible detent 27 at its inner end for catching the back of the plate 10, for locking the front member 12 on the plate and for being broken upon pivotal movement of the front member away from the plate as shown in broken lines in FIG. 2.

The key 26 is constructed of a frangible plastic resin such as Bakelite or the like. The key, as shown in FIG. 6, comprises a tab or handle 28 at its outer end, and a stem or shank 29 having the detent 27 on its upper inner end. Preferably, the shank is bifurcated to provide resilient, yieldable upper and lower shank portions 30 and 31 so that the upper portion yields as the detent is inserted into the slot 25 and enables the detent to catch the plate 10 after passing through the slot. Breaking of the detent upon separation of the front member 12 from the plate is facilitated by notching the key near the detent, for example, at 32. Also, as shown in FIGS. 2 and 6, the key handle has upper and lower wings 33a and 33b provided with inwardly facing edges adapted to be received by the recesses 23a and 23b, respectively. Thus, by making the wings of a different size the key cannot be installed upsidedown.

In order to enable an authorized person to open the box without breaking the key 26, the top wall 18 has an opening 34 above the keyway 24 and the keyway has an upper side opening 35 in registry with the opening 34 (FIG. 5) so that an instrument can be inserted through these openings to depress the upper shank portion 30 and release the detent 27. The opening 34 is concealed by the upwardly extending front and sidewall portions so as not to invite tampering. Further precaution against tampering can be taken by providing the openings 34 and 35 with a special configuration so that only an instrument in the hands of authorized persons can be inserted through these openings to release the detent.

Preferably, the opening 35 is at the inner or free end of the keyway 24 so that a rearwardly facing surface 36 (FIG. 5) is provided which is engaged by the detent to thereby maintain the key in assembly with its keyway when the box is opened for the purpose of inspection or testing.

In operation, the box is locked by holding the front member 12 against the plate and inserting the key 26. The apparatus is operated by exerting a suflicient pull on the handle H to break the detent and to allow the front member to release the switch element 17 whereupon an alarm is sounded. The alarm continues until an authorized person inserts a new key to re-lock the box.

Should a person tamper with the apparatus and cause the detent to break, the front member is pushed outwardly by the spring urged element 17 and drops down (FIG. 2) by reason of being pivoted at its lower end and its center of mass being outward of the pivot point. Such person will be unable to re-lock the box and the alarm will continue unless the person holds the box shut by hand which however would lead to detecting the person tampering with the apparatus.

When the box is open for any reason whatsoever, it gives a clear visible indication that it should be re-locked with a new key.

From the foregoing description, it will be seen that the present invention provides alarm signal station apparatus which is readily operated and re-set but discourages tampering.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

We claim:

1. In alarm signal station apparatus, the combination of a front member serving as a handle, a back member for mounting the apparatus on wall structure, hinge means connecting the lower edges of said members for pivotally mounting said members for movement toward and away from each other, a switch mounted on one of said members having a movable spring urged element engaged by the other of said members to place said switch in one position when said members are moved toward each other and in another position when said members are moved away from each other, one of said members being a box for concealing and enclosing said switch and the other of said members being a closure for the box, said front member having a keyway extending therethrough from front to back and said back member having a slot extending therethrough and in alignment with said keyway when the box is closed by the closure, and a key structurally independent of said members and inserted into and extending through said keyway and said slot and having a frangible detent at its inner end for catching said back member to lock said members together and for being broken upon movement of said members away from each other to unlock said members.

2. Apparatus according to claim 1, wherein said key includes a resilient shank portion formed with said detent and adapted to yield in the opposite direction in which said detent faces to facilitate insertion of said detent through said slot.

3. Apparatus according to claim 2, wherein said keyway has a side opening, and the box has an opening in registry with said side opening when the box is closed for inserting an instrument to press said shank portion and release said detent to thereby unlock said members without breaking said detent.

4. Apparatus according to claim 3, wherein the box 85 st ucture for concealing said last mentioned opening.

5. Apparatus according to claim 3, wherein said keyway is formed with structure engaged by said detent when said detent is released from said back member to maintain said key in assembly with said front member.

6. Apparatus according to claim 1, wherein said key includes a pair of bifurcated resilient shank portions, and said detent is formed on one of said portions.

7. In alarm signal station apparatus, the combination of a back plate for mounting the apparatus on wall struc ture, a push button switch mounted on said plate having a forwardly facing operating element, a front box closed by said plate for concealing and enclosing said switch and having a front wall for operating said switch element, hinge means connecting the lower edges of said plate and said box for pivotally mounting one end of said box on one end of said plate, a boss on the back of said front wall formed with a keyway extending from front to back, said back plate having a slot in registry with said keyway when said plate closes said box, and a key structurally independent of said plate and said box and inserted into and extending through said keyway and said slot and having a frangible detent for catching the back of said plate.

8. Apparatus according to claim 7, wherein said key includes a yieldable element formed with said detent at the upper edge thereof, said keyway has an opening at the top thereof, and the top wall of said box has an opening in registry with said keyway opening for inserting an instrument to release said detent.

9. Apparatus according to claim 8, wherein said box has front and side wall portions extending upwardly from its top Wall for concealing said last mentioned opening, said front wall portion serving as a pull handle.

10. Apparatus according to claim 8, wherein said keyway opening is at the rear of said boss and provides a face engaged by said detent when said detent is released from said plate to maintain said key in assembly with said'box.

11. In signal station apparatus, the combination of a back member for mounting the apparatus on wall structure, switch means mounted on said back member, a front member cooperating with said back member to provide a closed box for concealing and enclosing said switch means, hinge means connecting the lower edges of said members for pivotally mounting said front member on said back member to enable the box to be opened for access to said switch means, said front member having a keyway extending therethrough from front to back and said back member having a slot extending therethrough and in alignment with said keyway when the box is closed, and a key structurally independent of said members and inserted into and extending through said keyway and said slot and having a frangible detent at its inner end for catching said back member to lock said members together and for being broken upon pivotal movement of said front member away from said back member.

12. Apparatus according to claim 11, wherein said key includes a resilient shank portion formed with said detent and adapted to yield in the opposite direction in which said detent faces to facilitate insertion of said detent through said slot.

13. Apparatus according to claim 12, wherein said keyway has a side opening, and the box has an opening in registry with said side opening when the box is closed .for inserting an instrument to press said shank portion and release said detent to thereby unlock said members without breaking said detent.

14. Apparatus according to claim 13, wherein the box has structure for concealing said last mentioned opening.

15. Apparatus according to claim 13, wherein said keyway is formed with structure engaged by said detent when said detent is released from said back member to maintain said key in assembly with said front member.

16. Apparatus according to claim 11, wherein said key includes a pair of bifurcated resilient shank portions, and said detent is formed on one of said portions.

17. Apparatus according to claim 1, wherein diiferently dimensioned recesses are provided at opposite sides of said keyway at the front thereof, and said key has differently dimensioned portions at opposite sides each correpsonding to the dimensions of only one of said recesses and adapted to fit therein, whereby said key can only be installed in one position.

References Cited by the Examiner UNITED STATES PATENTS 2,427,134 9/1947 Gronbeck 200--169 5 2,789,188 4/1957 Korabowski 20 0-168 2,830,143 4/1958 Kooprnan 200-468 3,110,792 11/1963 Gauthier 200169 X KATHLEEN H. CLAFFY, Primary Examiner.

10 H. O. JONES, Assistant Examiner. 

7. IN ALARM STATION APPARATUS, THE COMBINATION OF A BACK PLATE FOR MOUNTING THE APPARATUS ON WALL STRUCTURE, A PUSH BUTTON SWITCH MOUNTED ON SAID PLATE HAVING A FORWARDLY FACING OPERATING ELEMENT, A FRONT BOX CLOSED BY SAID PLATE FOR CONCEALING AND ENCLOSING SAID SWITCH AND HAVING A FRONT WALL FOR OPERATING SAID SWITCH ELEMENT, HINGE MEANS CONNECTING THE LOWER EDGES OF SAID PLATE AND SAID BOX FOR PIVOTALLY MOUNTING ONE END OF SAID BOX ON ONE END OF SAID PLATE, A BOSS ON THE BACK OF SAID FRONT WALL FORMED WITH A KEYWAY EXTENDING FROM FRONT TO BACK, SAID BACK PLATE HAVING A SLOT IN REGISTRY WITH SAID KEYWAY WHEN SAID PLATE CLOSES SAID BOX, AND A KEY STRUCTURALLY INDEPENDENT OF SAID PLATE AND SAID BOX AND INSERTED INTO AND EXTENDING THROUGH SAID KEYWAY AND SAID SLOT AND HAVING A FRANGIBLE DETENT FOR CATCHING THE BACK OF SAID PLATE. 